Lxllow  lever transducer



1965 D. R. TREFFEISEN 3,219,778

HOLLOW LEVER TRANSDUCER Filed Sept. '7, 1962 INVENTOR.

o DU/VAL A. TREFFE/SE/V LOAD | o tjmow JMeZZ :Itl A TTQR/VEY United States Patent 3,21%,778 HQLLQW LEVER TRANSDUCER Donal R. Treffeisen, Huntington gtation, N.Y., assignor to Sperry Rand Corporation, Great Neck, N.Y., a corporation of Delaware Filed Sept. 7, 11962, Ser. No. 222,tl57 9 Claims. (Cl. 2tltl83) This invention relates to a hollow lever transducer of the force input type having mechanical, hydraulic and electrical components. The improved transducer has particular utility with an automatic pilot system for dirigi- =ble craft to provide an electrical input to the system in accordance with the force command of a human pilot at a manually operable controller or flight stick.

The manually operable transducer of the present invention is an improvement over the strain type of stick force transducers shown in US. Letters Patent No. 2,408,770, issued October 8, 1946, to C. A. Frische et al., and US. Letters Patent No. 2,895,086, issued July 14, 1959, to R. H. Pettit. The transducer structures of the noted patents operate to provide an electrical output for an automatic pilot system that is proportional to the force exerted on the controller or stick by the manual effort of a human pilot or operator. The feel characteristics of these structures are dependent on the stretch in an included resilient mechanical component resulting from the force of the human operator exerted on the controller or flight stick. In the improved transducer, only relatively rigid mechanical components are utilized in the structure and its feel characteristics to the human operator are provided by hydraulic means of the self-balancing type that provide the resilient factor.

Accordingly, an object of the present invention is to provide a transducer of the force input type whose feel characteristics do not depend on the strain in a resilient mechanical element.

A feature of the invention resides in the inclusion in a force transducer of the character described of an hydraulic servo system having compressible components cooperatively engaged between the inside Wall of a hollow ended lever and a hand grip member having narrowly restricted angular motion with respect to the lever so as to center the member in relation to the lever in the absence of a manual force on the hand grip member and provide a differential pressure output depending on the manual force exerted on the hand grip member and provide a differential pressure output depending on the manual force exerted on the hand grip member to move it from its center position. The hydraulic servo system is preferably sealed with respect to the atmosphere to prevent contamination of the pressure fluid therein. The self-balancing characteristics of the system render it insensitive to external changes in temperature and pressure.

Another feature of the invention resides in the provision in the improved transducer of an off-on switch with a movable part operatively connected to the servo of the hydraulic system to off-condition the included pick-offcomponent when the hand grip member of the structure is in its center position with relation to the lever.

Further objects, features and structural details of the present invention will be apparent from the following description when read in relation to the accompanying drawing, wherein FIG. 1 is an elevation view of a preferred embodiment of the structure of the improved transducer in which the hand grip end of the lever component is shown in longitudinal cross section,

FIG. 2 is a cross sectional View taken on lines 2-2, in FIG. 1, and

FIG. 3 is a cross sectional view taken on lines 33, in FIG. 1.

As shown in the drawing, the rigid mechanical components of the improved transducer include a lever 10 of rigid tubular form that is mounted on a frame 11 by means of a universal joint 12. The load linkages pivoted to the lever ltl may provide suitable connections to the elevators and ailerons of an aircraft whose frame 11 includes a bearing for the joint 12. As the servos of an automatic pilot are also operatively connected to the elevators and ailerons of the craft, the included mechanical linkages between the noted movable surfaces of the craft and lever lltl cause the lever to follow the operations of the servos. The outputs of the electrical pickoff means included in the improved transducer is effective to command servo operation to obtain this result. It will accordingly be understood that when the automatic control system is operative, the force exerted by the human operator or pilot on the improved transducer is not directly effective to move the rigid lever 10. This is accomplished indirectly through the operation of the servos in accordance with the command output of the electrical pick-off of the force transducer. The movable mechanical component or load lever ill) of the improved combination includes a tubular or hollow end portion as shown in FIG. 1.

The second mechanical component of the improved transducer is provided by a rocker type member 13 that is mounted on lever ltl within the hollow end portion thereof by a swivel joint 14- or other suitable connection that permits relative angular motion between the parts. As shown in FIG. I, the member 13 is an arm or rod having an end 1'5 with a hand grip 16 fixed thereto to one side of the joint connection 14. End 15 of the rod member 1?: extends exteriorly of the hollow end of the lever 10 through an opening in an end cap 117 fixed to the lever. The manual force input to the transducer is provided by the hand of the human operator or pilot on the grip extension of the lever 163 provided by the hand grip 16. To balance the member 13, a counterweight 18 is fixedly connected to the end 119 of the member 13 on the other side of the curved joint 14-. A stop 20 in the form of a ring is mounted within the hollow tubular end portion of the lever lid to engage with the counterweight 1S and accordingly narrowly restrict the relative motion between the parts to the width of the spacing therebetween when the member 13 is in its center position with relation to the lever N and there is no manual force applied on the hand grip 16. The permitted relative motion between the mechanical component is so slight as to escape the feel of the human operator at the grip to. To the operator the grip l6 and lever 16 move together which is actually the case when the force exerted on the grip rs is suificient to engage the counterweight l8 and stop ring 20. This feature provides the force override for manual control necessary when the automatic system is off or inoperative without damage to the transducer. The connected lever and member components of the improved transducer are both of relatively rigid mechanical structure.

The feel characteristics of the improved transducer are provided by an hydraulic servo system of the self-balancing type in which oppositely paired compressible capsules 2l22 and 2344 are cooperatively engaged between the inside wall of the hollow or tubular end portion of the lever 10 and the portion 15 of the rod member 13 shown in FIGS. 1 and 2, located between the grip 16 and the swivel joint connection 14. The noted paired hydraulic components are further arranged in equidistantly spaced relation about the periphery of the portion 15 of the rod member 13 that the same engage so that the capsules 21-22 resist fore and aft motions of the hand grip 16 in relation to the lever and the capsules 23 and 24 resist transverse motions of the hand grip in relation to the lever. A servo means with a diflerential pressure output is included in the hydraulic system for each of the pairs of capsules provided to center the member 13. As shown in FIG. 1, the servo means provided in the system for capsules 21 and 22 include two bellows units 25 and 26 whose respective free ends are connected by means of link 27 to bellows 26, link 28 to bellows 25, and a differential rocker 29 connecting the links 27 and 28. As the described components of the system have no relatively movable parts through which fluid linkage can occur, the system is sealed with respect to the atmosphere. The anchored ends of the bellows 25 and 26 are suitably fixed to a crosspiece 30 that is fixedly mounted within the hollow end portion of the lever 10. The respective fluid lines 31 and 32 connect bellows units 25, 26 to the compressible capsules 21 and 22. Equal pressure exists in each of branches of the considered hydraulic system in the absence of a manual force on the hand grip 16 of member 13. Accordingly, after operation of the improved transducer, the pressure on the high pressure side of the self-balancing system exerts a force on the member through the related capsule to restore the member 13 to its center position with relation to the lever 10. In operation with a fore or aft force exerted on the hand grip 16 by the human operator, the movement permitted between the mechanical components enables the member 13 to unbalance the system and provide a differential pressure output from related paired capsules and servo means of the system that depends on the force exerted to move the grip from its center position to the limit provided by the stop 20. As the pressure in the related line schange, the high pressure bellows unit expands and the low pressure bellows unit contracts to move the output rocker 29 of the hydraulic system about its axis.

The hydraulic component of the improved transducer functions similarly when a force is exerted on the hand grip 16 in a transverse direction in relation to the lever 10 to move the member 13 with respect to the capsules 23, 24. The corresponding portion of the system shown in FIG. 1 in this regard includes a bellows unit 33 for capsule 23 whose fixed end is anchored to a second crosspiece 34 within the hollow end portion of the lever 10. A fluid line 35 connects the capsule 23 to the bellows unit 33. The link to the movable end of the bellows unit 33 is indicated at 36. The rocker connected to the end of the link 36 is indicated at 37. The bellows servo unit cooperating with unit 33, the link to the rocker 37, and the fluid line between the unit and capsule 24 do not appear in the drawing. The servo means included in the system is responsive to the differential pressure output of the paired capsules.

The output component of the improved force transducer is provided by suitable electrical pick-oh. means with fixed or stator parts mounted within the hollow end of the lever 10. The pick-01f related to capsules 21, 22

as indicated at 38 includes a movable or rotor part with a shaft extension on which the rocker 29 of the related hydraulic component is supported so as to provide an electrical output depending on the movement of the mechanical member 13 from its center position in relation to the capsule 2122 and lever 10. As shown in FIG. 1, the electrical pick-off 39 related to capsules 23, 24 is similarly arranged with the hollow end portion of the lever 10 with the shaft of its rotor supporting the rocker 37 The relation between the component is such that when the hand grip 16 is centered in relation to lever 10 there is a null output from the electrical pick-oils 38 and 39. Openings are provided in the lever 10 for the input and output cables indicated respectively at 40 and 41 for the pickoff components 38 and 39. The rotor shafting between the respective rockers 29 and 37 operatively connects the servo means of the hydraulic components to the respective electrical pick-off components 38 and 39.

The improved force transducer shown in FIG. 1 further includes electrical oft-on switching means with a part operatively connected to the servo means to off-condition the pick-off means when the member 13 is in its center position. As shown in relation to pick-ofl? 38, a conventional off-on electrical switch 42 fixed within the tubular end portion of the lever 10 is connected to the output cable 41 to off-condition pick-ofl 38 when the member 13 is centered in relation to capsules 21-22. The operative or movable part of the switch 42 effects this result through a connecting link 43 to the rocker 29 of the related servo means hydraulic component. With manual force exerted on the hand grip 16 to unbalance the hydraulic servo system including the capsules 21-22, the link 43 is moved by the rocker 29 to on-condition the switching means 42 monitoring the related pick-off 38.

While the invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in its broader aspects.

What is claimed is:

l. A force transducer including a manually operable controller having a load lever with a hollow end portion, a balanced member with narrowly restricted universal motion in relation to the lever connected by a swivel joint within the hollow end portion of the lever having an end with a hand grip extending exteriorly of the hollow end portion of the lever to one side of the swivel joint and an end with a counterweight connected to the member within the hollow end portion of the lever to the other side of the swivel joint; a sealed, self-balancing hydraulic system within the hollow end portion of the lever having oppositely paired compressible capsules cooperatively engaged between the inside wall of the hollow end portion of the lever and the member to center the member in relation to the lever in the absence of a manual force on the hand grip of the member and provide a differential pressure output depending on the manual force exerted on the hand grip to move the member from its center position, servo means having diflerentially movable output components, and fluid lines connecting the respective output components of the servo means and the paired capsules; and electrical pick-off means having parts within the hollow end portion of the lever fixed to the lever and operative parts connected to the respective output components of the servo means of the hydraulic system.

2. A transducer of the character claimed in claim 1, in which the lever is a rigid tube, the member is a rod, and the hydraulic system includes two pairs of capsules arranged in equidistantly spaced relation about the periphery of the rod at one end of the tube.

3. A transducer of the character claimed in claim 1, including electrical off-on switching means having a part fixed within the hollow end portion of the lever and a part operatively connected to the servo means to off-condition the pick-off means when the member is in its center position.

4. A transducer of the character described including a manually operable controller having a load lever with a tubular end portion, a balanced member with narrowly restricted angular motion in relation to the lever connected Within the tubular end portion of the lever having an end with a hand grip extending exteriorly of the tubular end portion of the lever to one side of the connection and an end with a counterweight connected to the member within the tubular end portion of the lever to the other side of the connection; a self-balancing hydraulic system within the tubular end portion of the lever having a pair of oppositely arranged compressible capsules cooperatively engaged between the inside wall of the tubular end portion of the lever and the member to center the member in relation to the lever in the absence of a manual force on the hand grip of the member and provide a differential pressure output depending on the manual force exerted on the hand grip to move the member from its center position, servo means connected to the capsules by fluid lines responsive to the differential pressure output; and an electrical pick-oil within the tubular end portion of the lever having a fixed part connected to the lever and a movable part operatively connected to the servo means.

5. A transducer of the character claimed in claim 4, in which the member is a rod, and the capsules of the hydraulic system are located between the inside wall of the tubular end portion of the lever and the portion of the rod on the hand grip side of the connection.

6. A transducer of the character claimed in claim 4, including an electrical off-on switch having a part fixed within the tubular end portion of the lever and a part operatively connected to the servo means to oif-condition the pick-off when the member is in its center position.

7. In a transducer of the character described, a manually operable controller having a load lever with a hollow end portion, a member with narrowly restricted angular motion in relation to the lever connected by a pivot within the hollow end portion of the lever having an end with a hand grip extending exteriorly of the hollow end portion of the lever; a self-balancing hydraulic system within the hollow end portion of the lever having a pair of oppositely arranged compressible capsules cooperatively engaged between the inside Wall of the hollow end portion of the lever and the member to center the member in relation to the lever in the absence of a manual force on the hand grip of the member and provide a differential pressure output depending on the manual force exerted on the hand grip to move the member from its center position, a first servo connected to one of the capsules by a fluid line, a second servo connected to the other of the capsules by a fluid line, and means for connecting the servos to provide a differential output; and a pick-off having a fixed part within the hollow end portion of the lever and a movable part operatively connected to the diiferential output means.

8. In a transducer of the character described, a manually operable controller having a load lever with a hollow end portion, a member with narrowly restricted angular motion in relation to the lever connected by a pivot within the hollow end portion of the lever having an end with a hand grip extending exteriorly of the hollow end portion of the lever; and a self balancing hydraulic system having two opposingly arranged, compressible capsules cooperatively engaged between the inside wall of the hollow end portion of the lever and the member to center the member in relation to the lever in the absence of a manual force on the hand grip of the member and provide a differential pressure output depending on the manual force exerted on the hand grip to move the member from its center position and, servo means connected by respective fluid lines to the capsules to provide a diiterenial output.

9. A transducer of the character claimed in claim 8, including an electrical pick-01f having a fixed part and a movable part connected to the servo means.

References Cited by the Examiner UNITED STATES PATENTS 2,456,869 12/1948 Fowler -545 2,556,288 6/1951 Milster 60-54.5 2,895,086 7/1959 Pettit 317-99 3,056,867 10/1962 Eitel 200 81 BERNARD A. GILHEANY, Primary Examiner. 

1. A FORCE TRANSDUCER INCLUDING A MANUALLY OPERABLE CONTROLLER HAVING A LOAD LEVER WITH A HOLLOW END PORTION, A BALANCED MEMBER WITH NARROWLY RESTRICTED UNIVERSAL MOTION IN RELATION TO THE LEVER CONNECTED BY A SWIVEL JOINT WITHIN THE HOLLOW END PORTION OF THE LEVER HAVING AN END WITH A HAND GRIP EXTENDING EXTERIORLY OF THE HOLLOW END PORTION OF THE LEVER TO ONE SIDE OF THE SWIVEL JOINT AND AN END WITH A COUNTERWEIGHT CONNECTED TO THE MEMBER WITHIN THE HOLLOW END PORTION OF THE LEVER TO THE OTHER SIDE OF THE SWIVEL JOINT; A SEALED, SELF-BALANCING HYDRAULIC SYSTEM WITHIN THE HOLLOW END PORTION OF THE LEVER HAVING OPPOSITELY PAIRED COMPRESSIBLE CAPSULES COOPERATIVELY ENGAGED BETWEEN THE INSIDE WALL OF THE HOLLOW END PORTION OF THE LEVER AND THE MEMBER TO CENTER THE MEMBER IN RELATION TO THE LEVER IN TEH ABSENCE OF A MANUAL FORCE ON THE HAND GRIP OF THE MEMBER AND PROVIDE A DIFFERENTIAL PRESSURE OUTPUT DEPENDING ON THE MANUAL FORCE EXERTED ON THE HAND GRIP TO MOVE THE MEMBER FROM ITS CENTER POSITION, SERVO MEANS HAVING DIFFERENTIALLY MOVABLE OUTPUT COMPONENTS, AND FLUID LINES CONNECTING THE RESPECTIVE OUTPUT COMPONENTS OF THE SERVO MEANS AND THE PAIRED CAPSULES; AND ELECTRICAL PICK-OFF MEANS HAVING PARTS WITHIN THE HOLLOW END PORTION OF THE LEVER FIXED TO THE LEVER AND OPERATIVE PARTS CONNECTED TO THE RESPECTIVE OUTPUT CONPONENTS OF THE SERVO MEANS OF THE HYDRAULIC SYSTEM. 